连作烟田土壤根系分泌物的变化和分解

为阐明烟田土壤中根系分泌物的变化规律及确定具有化感作用的根系分泌物种类，研究分析了种烟1年、连作2年和连作3年0~20 cm、20~40 cm烟田土壤中根系分泌物的含量变化，并通过室内试验研究了烟草根系分泌物的分解转化。结果表明：（1）烟田土壤中含量较高的根系分泌物种类有苯甲酸、4-羟基苯乙酸、3-甲氧基-4-羟基苯乙酸和邻苯二甲酸二辛酯，其中4-羟基苯乙酸含量最高，含量较低的种类有4-羟基丁酸和甘油；（2）羟基丁酸、3-甲基-2-羟基丁酸、4-羟基丁酸、肉桂酸、油酸、硬脂酸酰胺和烟碱对烟草无直接化感作用；（3）室内试验表明，肉桂酸、3-甲氧基-4-羟基苯乙酸、邻苯二甲酸、3-羟基苯甲酸、邻苯二甲酸二辛酯、4-羟基苯乙酸和肉豆蔻酸的分解转化率均小于50%；（4）初步判定具有化感作用的根系分泌物种类包括：苯甲酸、3-羟基苯甲酸、4-羟基苯甲酸、月桂酸、邻苯二甲酸、3-甲氧基-4-羟基苯乙酸、3，4-二羟基苯甲酸、肉豆蔻酸、棕榈酸、9，12-十八碳二烯酸、苯丙酸、东良菪素、肉桂酸、邻苯二甲酸二辛酯和4-羟基苯乙酸。

The Changes and Degradation of Tobacco Root Exudates in Tobacco Fieldwith Continuous Cropping

We analyzed contents of tobacco root exudates in 0-20 cm and 20-40 cm soil where tobacco had grown for 1 year, 2 years,and 3 years in order to investigate variation of exudates in tobacco field and identify allelochemicals. The results showed that thecontent of benzoic acid, 4-hydroxyphenylacetic acid, 3-oxygen-4-hydroxyphenylacetic acid and phthalic acid dioctyl ester in tobaccofield were high, of which 4-hydroxyphenylacetic acid was the highest, and the content of 4-hydroxybutyric acid and glycerin werelow. Hydroxybutyric acid, 3-methyl-2-hydroxy butyric acid, 4-hydroxybutyric acid, cinnamic acid, oleic acid, stearic acid amide andnicotine had no direct allelopathic influence to tobacco. The decomposition rates of cinnamic acid, 3-methoxy-4-hydroxyphenylacetic acid, phthalic acid, 3-hydroxy benzoic acid, dioctyl phthalate, 4-hydroxyphenyl acetic acid and myristic acid were less than50%. We proposed that the following acids were allelochemicals, including benzoic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoicacid, lauric acid, oterephthalic acid, 3-methoxy-4-hydroxyphenyl acetic acid, 3,4-dihydroxybenzoic acid, myristic acid, palmitic acid,9,12-octadecadienoic acid, acrylic acid, scopoletin, cinnamic acid, phthalic acid dioctyl phthalate and 4 - hydroxyphenylacetic acid.